Outcomes of patients undergoing elective DC cardioversion for atrial fibrillation: a district general hospital experience.

Abstract

Atrial fibrillation (AF) is the most common cardiac arrhythmia seen in the adult population, affecting around 1-2% of those above the age of 18. For newly diagnosed patients, DC Cardioversion (DCCV) is an effective method of restoring normal sinus rhythm in those where rhythm control strategy is considered. The earlier DCCV is performed, the higher the likelihood of successful conversion to sinus rhythm. However, in practice, long waiting times may preclude any benefit of early DCCV. The aim of our audit was to evaluate the outcomes of patients undergoing DCCV in a large district general hospital and to evaluate the factors that could predict restoration of sinus rhythm including the effect of waiting times. This was a retrospective audit involving patients who had undergone an elective DCCV during the year 2021 at our hospital. Results A total of 247 patients were booked for DCCV, but 4 patients did not proceed (three were in sinus rhythm and one patient failed sedation). The remaining 243 patients (mean age 67.5+11.7 years, 66.5% male) were included in the analysis. Hypertension (62.1%) was the commonest co-morbidity, followed by hypercholesterolemia (53.2%). Eighty-nine patients (35.9%) had undergone a previous DCCV with a median delay 341(189-667) days since the initial cardioversion. The median delay from the decision for DCCV was 265 (107- 816) days. At the time of diagnosis, a decision for rate control was initially made in 159 (64%) of patients, with the remaining being put forward for DCCV directly. Those who were for rate control initially had a longer wait for the DCCV (308(134-1066) vs 114(57-376) p<0.001) Amiodarone was started in 70(28.3%) patients. At the time of diagnosis, all patients had a dilated left atrium (LA) by diameter, though 54 had normal LA volume. Of these 243 patients, 227 received one shock, 14 patients received two shocks and two received three shocks. DCCV was immediately successful in 232 (93.1%) patients and of this, 226 (91.5%) remained in sinus rhythm (SR) when discharged that day. This number fell to 120 (48.6%) at 6 months and 103 (41.7%) at one year. Those who maintained SR at discharge had lower number of shocks (p<0.001). Lower number of shocks also predicted those who maintained SR at 6 months and one year. Those who maintained SR at one year also were likely to have amiodarone continued post DCCV (p=0.01). There was no difference in other factors including demographics, risk factors, the delay in DCCV from diagnosis or the left atrial size between those who maintained SR either at discharge or during follow up and those who reverted to AF. The initial decision for DCCV or rate control did not affect the outcome of the DCCV. This however, could reflect the long waiting times in both groups. Conclusion In our audit, most patients waited significant durations before getting their elective cardioversion especially where the decision for rate control was taken initially. Only around half of patients maintained SR at one year, which could be a reflection of the delay in getting the DCCV and the dilated LA, which in turn could be a reflection of the delays. Amiodarone needs to be continued post DCCV in accordance with the guidelines as this affects long term maintenance of SR.